巨细胞病毒（英语：Cytomegalovirus，简称CMV）是一种疱疹病毒。感染人类的品种称 human CMV (HCMV) 或Human herpesvirus-5 (HHV-5)，是巨细胞病毒中研究最深入的

在人类和哺乳动物中，CMV感染一般发生在唾液腺。CMV在健康人身体中通常难以察觉，但有时可能是致命的，例如HIV感染者，器官移植，新生儿等。它可以引起婴幼儿水肿。感染后，CMV仍然能长期潜伏在体内。

Cytomegalovirus (from the Greek cyto-, "cell", and megalo-, "large") is a genus of viruses in the order Herpesvirales, in the family Herpesviridae, in the subfamily Betaherpesvirinae. Human and monkeys serve as natural hosts. There are currently eight species in this genus including the type species human herpesvirus 5 (HHV-5). Diseases associated with HHV-5 include mononucleosis, and pneumonias. It is typically abbreviated as CMV.